The present application relates to a single-wall carbon nanotube heterojunction and a method of manufacturing the same and a semiconductor device and a method of manufacturing the same and is suitably applied to, for example, a field effect transistor (FET) that uses a single-wall carbon nanotube as a channel material.
Since the single-wall carbon nanotube shows high mobility, it is expected that the single-wall carbon nanotube is applied as a channel material for a fast switching FET (see, for example, T. Durkop, S. A. Getty, Enrique Cobas, and M. S. Fuhrer, Nanolett., 4 (2004)35). In general, when an FET is manufactured using the single-wall carbon nanotube, a process for the manufacturing is roughly divided into two. One is a method of synthesizing a high purity single-wall carbon nanotube and, then, producing a single-wall carbon nanotube dispersed liquid and applying the single-wall carbon nanotube dispersed liquid to a predetermined position on a substrate. The other is a technique for arranging a catalyst in a predetermined position on a substrate, directly growing a single-wall carbon nanotube from this catalyst, and orienting the single-wall carbon nanotube. At present, since the latter on-board direct growth method has advantages that a single-wall carbon nanotube with high mobility can be obtained and the method is also applicable to a micro process, the method is studied by many researchers.
In recent years, it has become possible to synthesize a high purity single-wall carbon nanotube according to the chemical vapor deposition (CVD) method using Fe, Ni, and Co or alloy particulates containing these kinds of metal. It is becoming possible to control a radius of a single-wall carbon nanotube to some degree according to a laser abrasion method (see, for example, M. Shiraishi, T. Takenobu, A. Yamada, M. Ata, and H. Kataura, Chem. Phys. Lett., 358 (2002)213), zeolite supported catalyst having a uniform sub-nano-scale radius (see, for example, J.-F. Colomer, C. Stephan, S. Lefrant, G. V. Tendeloo, I. Willems, Z. Konya, A. Fonseca, Ch. Laurent, and J. B. Nagy, Chem. Phys. Lett. 317 (2000)83, J.-f. Colomer, J.-M. Benoit, C. Stephan, S. Lefrant, G. Van Tendeloo, and J. B. Nagy, Chem. Phys. Lett. 345 (2001)11, S. Tang, Z. Zhong, Z. Xiong, L. Sun, L. Liu, J. Lin, Z. X. Shen, and K. L. Tan, Chem. Phys. Lett. 350 (2001)19, K. Mukhopadhyay, A. Koshio, N. Tanaka, and H. Shinohara, Jpn. J. Appl. Phys. 37 (1998)L1257, and K. Mukhopadhyay, A. Koshio, T. Sugai, N. Tanaka, H. Shinohara, Z. Konya, J. B. Nagy, Chem. Phys Lett. 303 (1999)117), and a catalyst synthesizing technique that uses organic polymer containing metal as a precursor. A problem in an actual process for manufacturing an element based on an FET is deterioration in an element characteristic due to mixing of metallic single-wall carbon nanotubes in semiconductive single-wall carbon nanotubes. However, it is difficult to control, in a step of synthesizing single-wall carbon nanotubes, the semiconductive single-wall carbon nanotubes and the metallic single-wall carbon nanotubes with a very small difference (equal to or smaller than 0.01 nanometer) in tube diameters. Therefore, under the present situation, results of researches for a technique for separating the semiconductive single-wall carbon nanotubes and the metallic single-wall carbon nanotubes are extremely limited as described below.
Methods proposed to date in order to solve this problem include (1) separation of the semiconductive single-wall carbon nanotubes and the metallic single-wall carbon nanotubes by chemical treatment (see, for example, M. S. Strano, et al, JPC. B 108 (2004)15560, M. S. Strano, et al, Nano Lett. 4 (2004)543, M. S. Strano, et al, JACS. 125 (2003)16148, and M. S. Strano, et al, Science 302 (2003)1545), (2) electrical breakdown of the metallic single-wall carbon nanotubes (see, for example, R. Martel, T. Schmidt, H. R. Shea, T. Hertel, Ph. Avouris, Appl. Phys. Lett. 73 (1998)2447), and (3) insulation of the metallic single-wall carbon nanotubes by chemical modification. Among these methods, at present, (1) separation by chemical treatment is set as an ultimate technical target among subjects for realizing a semiconductor device employing the semiconductive single-wall carbon nanotubes. As this method of separation by post treatment of synthesizing, selective absorption to the metallic or semiconducting single-wall carbon nanotubes uses chemicals (see M. S. Strano, et al, Science 301 (2003)1519). However, no other remarkable results are reported. In the case of the chemical separation method, a high separation ratio is necessary in an actual operation of the FET. For example, to cause 90% or more of a single-wall carbon nanotube FET, in which five carbon nanotubes bridges a source electrode and a drain electrode, to operate, it is necessary to set an abundance ratio of the semiconductive single-wall carbon nanotubes to 98%. Judging from these examples of reports, under the present situation, a clear method for solving the deterioration in an FET characteristic due to mixing of the metallic single-wall carbon nanotubes in the semiconductive single-wall carbon nanotubes has not been established yet.
On the basis of an operation characteristic of a single-wall carbon nanotube FET employing single-wall carbon nanotubes synthesized at 600° C. according to a plasma enhanced chemical vapor deposition (PECVD) method using a catalyst produced from an Fe thin film and using a methane (CH4) gas as a carbon material, it is reported that about 90% of single-wall carbon nanotubes synthesized by the PECVD method are semiconductive single-wall carbon nanotubes (see Y. Li and H. Dai, et al, Nano Lett., 4, 2 (2004)317). However, in this report, there is no reference to a ground and a theory for the selective growth of the semiconductive single-wall carbon nanotubes at the abundance ratio of 90% by the PECVD method.
As described above, in the techniques in the past, it is difficult to prevent the deterioration in the characteristic of the single-wall carbon nanotube FET due to mixing of the metallic single-wall carbon nanotubes in the semiconductive single-wall carbon nanotubes.